Nowadays, poorly soluble active ingredients represent a major technological challenge in the development of oral dosage forms. Fenofibrate is a poorly soluble prodrug, which is used to treat hyperlipidemia and belongs to class IIb according to the developmental classification system, meaning that complex technological approaches are needed to improve its solubility. With this aim, fenofibrate was incorporated into solid dispersions with non-ordered mesoporous silicon dioxide – Syloid® 244 FP. Solid dispersions with 30 % fenofibrate content were prepared by solvent evaporation using three different organic solvents, namely ethyl acetate, acetone, and isopropanol at different evaporation temperatures – at 40 °C and at the boiling temperature of each solvent at normal air pressure. We investigated the effect of the selected organic solvent and temperature on the properties of formulations and on the release of fenofibrate from freshly prepared samples, and after 4 and 8 weeks of storage at elevated temperature and relative humidity. The properties of the solid dispersions, including changes in the solid state and fenofibrate release, were evaluated by various methods and the results were compared with the pure prodrug and the physical mixture with the same composition. By preparing solid dispersions we managed to improve the dissolution of fenofibrate. We found that the drug release rate is higher with samples prepared at higher temperatures. It was also observed that good solubility of fenofibrate in solvent affects its physical properties, e. g. higher degree of amorphicity, and consequently faster release in an acidic medium. We also determined the optimal conditions for the preparation of solid dispersions, which were ethyl acetate as a solvent, at boiling temperature. Under these conditions, solid dispersions with different fenofibrate contents (20 %, 25 % and 35 %) were prepared. Apart from 35 % solid dispersions, they were all completely amorphous and their release profiles were comparable to the 30 % content sample. In post-aging samples, it was observed that, despite the higher proportion of crystalline fenofibrate, the release profiles at 4 and 8 weeks did not differ significantly from that of fresh samples. Interestingly, for some formulations, the release profile even improved compared to the initial tests. Although fenofibrate is prone to crystallisation, we were able to show that its amorphous state can be maintained by preparing solid dispersions. In the case of a 20 % fenofibrate content in the formulation, this can be achieved even after 8 weeks of aging at elevated conditions.
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